1. Field of the Invention
The present invention relates generally to etchants, primers and adhesive bonding systems and methods. More specifically, the present invention relates to primer compositions that are self-etching, and to simplified adhesive bonding systems using such compositions. The compositions and methods of the present invention enhance the bonding of dental adhesives, composites, and other dental prostheses to dentin, enamel and tooth tissue.
2. Background of the Invention
Recent advances in dental restorative techniques include the use of materials such as composite resins to effect tooth filling and restoration instead of metal amalgams. Other advances include the use of new dental components such as thin wire braces and other types of dental components made of metal, ceramics, resins or other bio-compatible substances. Depending on the clinical picture, such restoratives and components may need to be applied directly to the tooth dentin and/or enamel, or may need to be applied to other bio-compatible substrates such as metals, ceramics, resins or amalgams which may already exist in the patient and/or are to be added as part of the clinical treatment.
Common to the foregoing techniques, and many older forms of dental restorative techniques, is the general need for dental restorative techniques using etchants and primers which are simple to use. Ideally, the dental professional would use the etching, priming, and adhesive bonding systems in a manner that requires a minimum of time for the patient in the chair. In addition, such ideal etching, priming, and adhesive bonding systems would also provide bond strengths of the restorative or other dental component to the chosen dental substrate which approach the strength of the underlying substrates.
Several primer and adhesive bonding systems have been reported in the literature which have achieved some, but not all of the above-stated goals. A general discussion of multiple-component primer and adhesive bonding systems and their predecessors is set out in Suh, “I-Bond—Fourth Generation Dentin Bonding System,” J. Esthetic Dentistry, Vol. 3, No. 4, pp. 139–147 (July–August, 1991) and in Bowen U.S. Pat. No. 5,270,351 at Col. 1, lines 29-Col. 2, line 36 and Col. 2, lines 54–64, the disclosures of which are hereby incorporated by reference. “One-component” dental primer and adhesive bonding systems are generally disclosed in, for example, Blackwell et al. U.S. Pat. Nos. 4,657,941 and 4,816,495 and Huang et al. U.S. Pat. No. 4,966,934 all of which are assigned to Dentsply Research and Development Corporation (hereinafter also collectively referred to as the Dentsply patents), Bunker U.S. Pat. No. 5,304,585, which is assigned to 3M, and Suh et. al. U.S. Pat. No. 5,658,963, which is assigned to Bisco, Inc.
All of these etchant, primer and adhesive bonding systems generally require a first pretreatment step of the dental substrate with mordants and/or acidic solutions to decalcify and remove the smear layer and to etch tooth dentin and/or enamel before application of the dental adhesive, dental restorative or other component. This is generally referred to as the “bonding technique” because the dental restorative is applied to the dental substrate while it is still wet after rinsing with water to remove the etchant and/or primer solution. To further enhance bonding between the substrate and the multi-component dental restorative some of these systems also employ at least two additional primer or adhesive enhancing or bonding compounds which must either (1) be applied separately and sequentially to the dental substrate, (2) must be mixed together by the dental professional in the office immediately before use on the patient to prevent premature polymerization of the components (for example see Bowen U.S. Pat. Nos. 4,514,527; 4,551,550; 4,558,756, 4,659,751; 5,320,886; and 5,270,351; Suh U.S. Pat. No. 5,348,988; and Bunker U.S. Pat. No. 4,544,467; the disclosures of which are hereby incorporated by reference). Such multi-component/multi-step methods necessarily require the dental professional to perform an initial etching step followed by a separate rinsing step as well as a step of admixing of primers and/or primers and initiator while the patient waits in the chair, unnecessarily complicating the overall restorative process and increasing the treatment time for the patient. Moreover such systems generally require the use of an additional component, an adhesive bonding resin, applied as an additional step in the process in order to achieve such high bond strengths, further complicating the restorative process. Even the use of “one-component” dental primer and adhesive bonding systems on tooth dentin and/or enamel substrates is still often preceded by an initial pretreatment step of “etching” or decalcifying the dental substrate with an acidic solution followed by rinsing step(s) to remove most or all of the etchant composition and subsequently followed by application and bonding of the dental restorative or luting composite by copolymerization through light-curing or self-curing.
Other commercial self-etching priming systems include Clearfil SE Bond (a/k/a MegaBond, Kuraray Corporation) a two component self-etching primer adhesive system including a methacryloyloxydecyl dihydrogen phosphate (MDP) primer solution and a MDP/bonding resin solution applied sequentially to the tooth surface. SE Bond requires light-curing and cannot be applied to indirect restoration procedures because of the thickness of the film. It also exhibits poor enamel etching, requiring conventional acid etching on uncut enamel. Another light-cure only self-etching adhesive system is Prompt L-Pop sold by ESPE/3M. The manufacturer indicates that this all-in-one self-etching adhesive system contains an organophosphate monomer. Different from SE Bond, this system does not need a priming procedure. The mixture of two components is applied to tooth surfaces right after they are mixed. It also is reported to exhibit poor bonding to tooth enamel and does not bond to self-cure materials.
U.S. Pat. No. 4,640,936 (issued Feb. 3, 1987 to Janda et al.) suggests the preparation and use of a dental composition consisting of a solution of (i) at least one phosphate selected from the group consisting of methacryloyloxyethyl dihydrogen phosphate and bis-(methacryloyloxyethyl) hydrogen phosphate and (ii) a photopolymerization catalyst comprising camphor quinone and an amine, in acetone. The composition is intended to be used with a separate photopolymerizable dental sealing composition.
U.S. Pat. No. 4,719,149 (issued Jan. 12, 1988 to Aasen et al.) describes the use of an acid and a water-soluble film former as a primer for hard tissue. The acid has a pKa less than or equal to that of phenol (i.e. less than or equal to 9.9), and the film former has a solubility in water of at least about 5 weight percent. The acid and film former are applied to the hard tissue either concurrently or sequentially. The primers were suggested as an adhesive for dentin, enamel, and other hard tissues.
U.S. Pat. No. 5,264,513 (issued Nov. 23, 1993 to Ikemura et al.) suggests the preparation of a dental composition containing water, a polymerizable compound having a hydroxyl group, a polymerizable compound having an acidic group, and a curing agent.
U.S. Pat. No. 5,834,532 (issued Nov. 10, 1998 to Yamamoto et al.) describes primer compositions containing a polymerizable monomer containing an acid group and an initiator. The patent further describes curable compositions that are useful for restoring tooth surface material.
U.S. Pat. No. 5,925,690 (issued Jul. 20, 1999 to Fuchigami et al.) describes a dental composition containing a phosphoric acid group-containing monomer, a carboxylic acid groups-containing monomer, and water. The composition provides adhesion to dentin and to enamel.
U.S. Pat. No. 6,245,872 (issued Jun. 12, 2001 to Frey et al.) provides a dental composition containing i) 10 to 90 parts by weight of at least one singly or repeatedly ethylenically unsaturated phosphoric acid ester, ii) 5 to 85 parts by weight of a solvent, iii) 0.01 to 5 parts by weight of an initiator which can form free radicals, and iv) 0 to 10 parts by weight of customary auxiliaries and additives. A tooth is treated with the composition, and immediately is coated with polymerizable filling material.
U.S. Patent Application Publication No. 2002/0019456 A1 (published Feb. 14, 2002 to Jia) suggests a composition comprising a solution of a SO3 terminated compound resin, and an optional fluoride source. The SO3 terminated monomer can include 2-acrylamido-2-methyl-propanesulfonic acid (AMPS), AMPS derivatives, 2-sulfoethyl methacrylate (SEM), SEM derivatives, 3-sulfopropyl methacrylate (SPM), SPM derivatives, or mixtures thereof. The composition is described as a self-etching primer. The compositions contain a solvent that may include water and/or a polar solvent partially or totally soluble in water. Various examples of the composition were presented, but stability data was not disclosed.
There is, therefore, a need in the art for the true self-etchant primer compositions that are capable of etching dentin and enamel in both self-curable and light-curable polymerization systems and can be applied and used without separate rinsing steps and which themselves are polymerizable within the dental curing systems to enhance bonding of the dental adhesive and/or dental restorative material to dentin and enamel and overall, permit a quicker, simpler, and easier restorative process, yet still provide a consistently high and stable bond strength of adhesives, composites, resins, metals and other dental prostheses to dentin, enamel, tooth tissue and to other substrates.